1. Field of the Invention
The invention relates to a throttle device.
2. Description of the Prior Art
In the automotive industry, by means of a throttle device disposed in an intake tube, the amount of air for combustion available to an internal combustion engine is controlled and/or regulated, so that as a result, the mechanical power output by the engine can be controlled and/or regulated.
For this purpose, the throttle device has a housing, a gas conduit embodied in the housing, a throttle shaft, and a throttle body disposed on the throttle shaft. The throttle shaft can be moved by means of an adjusting device, such as an electric motor, so that the throttle valve also executes a motion. As a result, the flow cross-sectional area available for the flow of air through the gas conduit can be varied. The throttle shaft is supported on the housing of the throttle device with a bearing, such as a roller hearing. Outside the roller bearing, between the housing and the throttle shaft, an interstice or gap occurs. Although the throttle shall is sealed off with respect to the housing by means of one or two sealing rings, nevertheless leaks can occur at these sealing rings. Fluids, that is, liquids or gases, can enter through this interstice or gap between the housing and the gas conduit. Especially when the throttle device is used in an internal combustion engine of a motor vehicle, condensate in the form of water can form in the gas conduit. In a turbocharged internal combustion engine, relatively high pressures also occur in the gas conduit, in the range of up to 3.5 bar. As a result, the water, in the form of condensate or air or gas, can reach the roller bearing and cause damage there. In turbocharged engines, the condensed water is also at that high pressure. If the condensed water in the gas conduit is located in the vicinity of the interstice or gap that opens into the gas conduit between the housing and the throttle shaft, then that condensed water is forced into that interstice with that high pressure as well.
From German Patent Disclosure DE 10 2004 043 125 A1, a throttle device for an internal combustion engine with a throttle valve housing and with a throttle valve shaft and a throttle valve is known. The throttle valve shaft is supported pivotably in the throttle valve housing in a bearing receptacle provided on the throttle valve housing and is pivotable with the aid of an adjusting device that engages the throttle valve shaft.